Holder for thread rolling tools



Nov. 16, 196 J. M. BURNETT ETAL. 3,

HOLDER FOR THREAD ROLLING TOOLS 2 Sheets-Sheet 1 Filed March 5, 1963 INVENTORS.

+914, fawn/57s:

N 1955 J. M. BURNETT ETAL 3, 7

HOLDER FOR THREAD ROLLING TOOLS Filed March 5, 1963 2 Sheets-Sheet 2 "ITTTY" INVENTORS JZwres 133177762 United States Patent 3,217,523 HOLDER FOR THREAD ROLLING T0015 James M. Burnett, Mount Clemens, and Herbert C.

Burnett, Roscville, Mich, assignors to Detroit Tap &

Tool Company, Warren, Mich, a corporation of Delaware Filed Mar. 5, 1963, Ser. No. 262,911 6 Claims. (Cl. 72-112) This invention relates to tool holding apparatus and more particularly to holder means for tools such as rolls for forming threads by thread rolling methods.

The tool holder of the present invention is particularly adapted for use with conventional automatic screw machinery for forming rolled threads; but is also suitable for precision knurling and burnishing, and for the rolling of oil grooves, serrations, etc. In such operations, the forming tools are conventionally mounted by holder means, or attachments, on slides of the machinery for movement to and from working engagement with a workpiece fixedly connected to the machinery spindle by a collet means for rotation relative to the forming tool or tools.

Ideally, the holder means should be as small as possible to occupy a minimum of space when installed and to permit access to small work areas. Further, the holder means should be capable of supporting tooling of varying sizes with minimal change and should be capable of handling maximum size tools. The spacing of the forming tool from the collet means, which hold the workpiece on the machine spindle, should be minimized to reduce loads on the spindle during forming operations. Standardization of the holder means to permit installation on varying screw machine designs without modification of the screw machine slides or of the holder means results in substantial savings in set-up time and installation costs. Similarly, the holder means is preferably adjustable on the machine and in the work area through a maximum range of adjustment with a minimum of adjusting operations requiring simple manipulations and little likelihood of error causing tool misalignment or the like. When pairs of tools, such as thread rolls, are supported on the tool holder for simultaneous forming engagement with a workpiece and cooperative action to attain a unitary result, it is necessary to provide positive synchronization means operative between the tools in a simplified manner requiring minimal adjutsment and having maximum reliability in use.

Accordingly, a primary object of the present invention is to provide a new and improved tool holder for thread forming rolls which is extremely compact and specially designed to permit engagement of the forming rolls with a workpiece closer to a screw machine collet or the like to promote better thread forming action.

A further object incorporated With the compact design is wide adaptability of the tool holder to existing mounting structure and slides of automatic screw machines and the like with little or no modification.

Another object is to provide a tool holder for thread rolling tools and the like which is readily adaptable to support varying size tools throughout a large range of sizes by merely adjusting standardized spacer members and associated pins. To this end, the basic tool holder construction is comprised of a minimum number of parts permitting a wide range of interchangeability at the work area. In particular, in the preferred form of the present invention, the tool holder body is comprised of only three parts comprising a pair of plate elements spaced by any one of a series of standardized block members.

Still another object of the present invention is to provide a tool holder having means to accommodate a wide diameter range of thread rolls. To this end, forming roll pockets provided in the tool holder are of maximum depth and special mounting means are provided to permit small diameter rolls and large diameter rolls to be supported equally well by a single set of tool holder components.

An additional object is to provide simplified tool supporting means within the tool holder completely eliminating floating supports and requiring only a simple adjustment at any given setting and also having means for providing multiple settings with a minimum of adjustment.

A further object of the present invention is to provide new and improved means for positively synchronizing roll action at the beginning of a work cycle independently of initial uniform contact or simultaneous contact of the forming rolls with a workpiece.

Another object is to provide new and improved eccentric means for changing the poistion of a forming tool support pin to better accommodate varying tool sizes. In addition, simplified adjustment means are provided to vary the spacing of the forming tools in any of various eccentric adjusted positions.

Still another object is to provide mounting means for holding the forming tools in a preferred position resulting in optimum forming results. To this end, the forming tools are mounted on adjustable support means movable toward and away from one another along paths of movement inclined relative to one another and extending non-perpendicularly to the axis of rotation of the workpiece.

The foregoing objects, and others, may be attained by utilization of the inventive principles hereinafter described in detail by reference to the accompanying drawing wherein:

FIGURE 1 is a plan view of an illustrative tool holder for forming tools, such as thread rolls, embodying the inventive principles;

FIGURE 2 is a sectional view taken along the line 2-2 in FIG. 1;

FIGURE 3 is a side elevational view taken along the line 33 in FIG. 1

FIGURE 4 is a sectional view taken along the line 44 in FIG. 1;

FIGURE 5 is a sectional view taken along the line 5-5 in FIG. 1; and

FIGURE 6 is a sectional view taken along the line 6-6 in FIG. 2.

Referring now to FIGS. 1 and 3, the tool holder 16 is shown mounted on a connecting block 12 of a slide 14 of an automatic screw machine or the like by a dove tail portion 16 and a locking plate 18. Suitable fastening means 20, 21 are adapted to secure the tool holder in place. In general, the tool holder 10 comprises a base portion 22 and spaced outwardly extending arm portions 24, 26 which are separated by and define a work cavity 28. Each of the arms is bifurcated to sup port thread forming dies 30, 32, in the form of cylindrical roll members, rotatably mounted on pin means 34, 36. During a thread forming operation, the tool holder is adapted to be moved by the automatic screw machine slide means 14 relative to a rotating workpiece W which is received in the cavity 28. The workpiece is rotatably connected to the machine spindle by collect means 38 shown in FIG. 3.

bers and the spacer member are identical and conjointly form the dovetail fastening portion 16. The plates are secured to the spacer block by suitable fastening means 46, 48 and 50, 52. The bifurcated arm portions are formed by the spaced plates, and preferably have identical peripheral outlines. Tool pockets are formed between the spaced plates and the front surface of the spacer block. Arcuate walls 54, 56 extend, respectively, from adjacent the side walls of the spacer block to a centrally located bridge portion'58 which terminates at the rear of the Work cavity 28 and separates the tool pockets. The bridge portion 58 provides continuous spacing support between the plates 4%), 42 from the rear of the tool holder to the work area and permits the arcuate walls 54, 56 to be of a diameter forming exceptionally deep tool pockets. The diameters are such that an extension of the arcuate walls into the work area 28 would result in intersection thereof. Accordingly, forming tools of maximum diameter may be utilized with the tool holder up to the point where the forming tools would be of a diameter causing interference with one another. Such an arrangement permits an extremely wide size range of forming tools to be used with a particular tool holder.

In addition, new and improved mounting means are provided to accommodate relatively small sized forming tools to extend and maximize the size range of tools usable with a particular tool holder. To this end, bushing means 60, 62 of special design are provided for mounting one of the pins 34. Each bushing, as may be seen by reference to bushing 60 in FIG. 1, comprises annular peripheral segments 64, 66 which are connected by parallel flat segments 68, 70. A pin aperture 72 is provided in each bushing to receive and retain the ends of the pin 34. The pin apertures are eccentrically formed in the bushing between the annular segments 64, 66 so that a relatively narrow wall portion 74 is provided at one end and a relatively thick wall portion 76 is provided at the other end. Correspondingly configured slots are formed in plates 40, 42 to receive the bushings. The center of the bushing slots are off-set towards the work area 28 relative to the center of the holder arm.

Mounting means are provided for each of the bushings enabling reversal of positions of the narrow wall portions 74 and the thick wall portions 76 so that the location of the pin 34 relative to the work area 28 and the workpiece W can be shifted between a maximumly spaced setting and a minimumly spaced setting to accommodate relatively large sized forming tools in the one setting and relatively small sized forming tools in the other setting. Annular support flanges 78, 79 are formed on the bottom of each bushing and are received on annular shoulders 80, 81 formed in the plates 40, 42 as shown in FIG. 2. Oppositely located slots 82, 83 and 84, 85 extend radially through the bushings to receive set screws 86, 87, respectively, threadably mounted in holes 88, 89 which terminate at the side surface of the tool holder for ready accessibility for tightening and loosening. The set screws also engage and hold the pin 34 in fixed position by means of suitable flats 90, 92 formed on the side of the pin opposite the apertures 88, 89. Accordingly, the position of the pin 34 is adjustable between two spaced settings by reversal of the bushings 60, 62.

Additional adjusting means are also provided to obtain multiple adjustments of forming tool spacing relative to the workpiece and relative to one another in each of the spaced settings provided by the eccentric bushings. The multiple adjustment means are associated with the other pin 36 and comprise elongated slot like apertures 96, 98 formed in the plates 40, 42, as shown in FIG. 2. Referring now to FIG. 1, each aperture comprises opposite annular peripheral segments 99, 100 which are separated by parallel side wall surfaces 102, 104. The center of the slots 96, 98 is preferably offset toward the work area 28 relative to the center of the arm of the tool holder. Consequently, when the pin 36 is in the rearwardmost position in the slots 96, 98 adjacent the side wall 1% of the tool holder away from the work area, the center of the pin 36 will approach coincidence with the center of the arm. In this manner, forming rolls of maximum diameter can be accommodated while at the same time providing for adaptability to forming tools of smaller diameter and maximum range of adjustment. It should also be noted that the path of adjusting movement of the pin 36 along the longitudinal centerline of slots 96, 98 is inclined outwardly toward the workpiece position and the longitudinal centerline of bushings 6t), 62 is similarly inclined.

The ends of the pin 36 are received in the slots 96, 98 with the parallel portions 102, 104 in substantial abutting engagement with the shaft periphery. The diameter of the pin is considerably smaller than the diameter of the annular segments 99, 160 to permit the position of the pin in the slot to be adjusted along the flat portions 102, 104 toward and away from the arcuate segments 99, 160. In order to locate and position the pin in any adjusted position within the slots, set screws 1118, 116 and 112, 114 are threadably mounted in apertures 113, 114 and 115, 116 in the plates 40, 42, respectively, The apertures 113, 115 terminate at the side walls of the tool holder for ready access and the apertures 114, 116 are outwardly skewed into the work area 28, as shown in FIG. 1, to provide ready access and maximum support for the pin. Flat portions 117, 118 are preferably formed on the ends of the pin opposite the set screws 1%, 112 for holding engagement therewith.

In order to obtain positive synchronization of the thread forming rolls 30, 32 in use, gear means are provided in the tool holder to positively connect the rolls. The gear train comprises gear elements 120, 122 which are rotatably mounted on the pins 34, 36 in gear cavities 126, 123 provided in the plate 4-2. The gears 120, 122 are provided with axially outwardly extending hubs and are drivingly connected to the rolls 30, 32 by means of radially outwardly extending lugs 130, 132 as shown in FIGURE 6. Slots 134, 136 provided in integral hub portions 138, 140 of the rolls receive the lugs. The slots 134, 136 are substantially wider than the lugs 130, 132 and permit limited movement of the gears relative to the rolls. Spring means 142, 144 are seated circumjacent the hub portions 138, 140 and are adapted to normally position the lugs in abutting engagement with side wall portions of the slots for driving engagement with the rolls during thread forming movement of the rolls relative to the workpiece; but also to permit relative movement between the rolls and the gears when necessary such as during initial engagement of the rolls with the workpiece when one roll contacts the workpiece before the other roll. The ends 146, 148 of the springs may be connected to the roll and the gear to bias the gear and the tool into the position shown in FIGURE 6.

The gear train is completed by gear elements 150, 152, 154 which are mounted in intersecting gear cavities 156, 158, in the plate 42. The gear elements 150, 154 are rotatably supported in the cavities 156, 160, respectively, by means of fastener devices 162, 164, each fastener having reduced shaft portions 166 provided at the end as shown in FIGURE 5. Plate means 170 extend completely across the plate 42 to enclose the gear train. The plate means 170 defines slots 171 and 172 in which are disposed guard members 173 carried by the hubs of the gears 120 and 122. The guard members thus move radially with the pins 34 and 36 when the pins are adjusted and thus provide a chip guard and seal for the gear train in all positions of the pins 34 and 36.

Referring now to FIGURE 4, gear 152 is rotatably mounted on the shank 174 of the bolt element 176. A

bushing 178 provides a shoulder 180 for one side of the gear and the plate 170 provides a bearing shoulder 182 on the other side of the gear. A snap ring 184 is provided on the bolt shank which has a portion 186 threadably mounted in an aperture 188 in the spacer block 44.

The tool holder is designed to accommodate an unusually wide width range of rolls by change of the spacer block 44 to any of a number of other similarly configured spacers of varying widths. In order to accommodate varying width spacers, the only other tool holder parts which may require change are the pins. By providing standard size pins of varying lengths, the change of parts may be greatly simplified. None of the adjustment mechanism, gear mechanism, or synchronization mechanism need be changed. The plate 40 is designed to be of minimum thickness and is substantially thinner than the plate 42. The thickness of the plate 40 is minimized by placing all of the gear members in the plate 42 and by minimizing the number of adjustment features contained in plate 40. Accordingly, the tool holder can be positioned much closer to the machine collet than in previous devices. In this manner, machine spindle loads are minimized since the distance between contact of the forming tools with the workpiece and the connection to the spindle are minimized. Furthermore, the extremely deep tool pockets formed by the spacer block design enables use of larger diameter rolls and forming of greater workpiece diameters than any other thread roll holder of comparable size. All standard threads from N0. to 1%" size can be rolled with only two standard tool holder sizes.

The provision of the eccentric bushings on one of the tool support pins and simple set screw adjustments provided on the other pin enable shop floor roll adjustment by simple operations. Since there are no floating arms or the like, the adjustments are vastly simplified. The setting of the one roll may be varied between the two eccentric positions and the other roll is infinitely adjustable within its slots by the provision of the simplified set screw arrangement.

For example, we have been able to provide one size tool holder to accommodate tools for roll forming No. 10 to threads and another larger size tool holder for idential design for roll forming A" to 1%" threads. For the small size tool holder, we provide standardized spacer blocks of 1", 1%", 1 /2" and 1%" widths, and for the large size tool holder standardized spacer blocks of 1%", 1 /2, 1%" and 2 widths. The small size tool holder has a length from front to back, as shown in FIG. 3, of approximately 3" and the large size tool holder has a length of approximately 3%. The width of the tool holder from side to side, as viewed in FIG. 1, is approximately 3%" for the small size and 5%" for the large size. The depth of the tool holders from opposite sides of the plates 40, 42 as viewed in FIG. 3, is approximately 2%" for the small size and 2% for the large size. The thickness of plate 40 is approximately in the small size tool holder and only /8" in the large size tool holder. Since the plate 40 is adapted to be mounted closely adjacent the collet face of an automatic screw machine, the distance from the machine spindle-workpiece connection is minimized to reduce machine spindle loads. It will be readily apparent that an extremely compact tool holder design is provided for forming tools producing an unusually large range of thread sizes and lengths.

The spring connections between the gears 120, 122 and the rolls 30, 32 provide positive synchronization between the rolls regardless of which roll contacts the workpiece first. The positive synchronization means are provided between both rolls and therefore are effective regardless of the position of the rolls relative to one another and relative to the workpiece at any given condition of contact. As may be clearly seen by referring to FIGURE 1, the axes of rotation of the gear elements are arranged along a U-shaped arc. Thus, lines drawn between the axes of rotation of the gear elements 120, 154 and between the axes of rotation of the gear elements 122, are not parallel but rather intersecting. Thus, forces applied to the gear train during rolling operation through the gear elements 120, 122 are applied tangentially to the connecting gear elements 150, 154.

Since the inventive principles hereinbefore disclosed are susceptible of use in varying combinations and in alternative embodiments of the invention, it is intended that the appended claims be construed to include all applications of the inventive principles except insofar as limited by the prior art.

The invention claimed is:

1. A tool holder for thread rolling tools or the like comprising standardized separable and changeable spaced plate members, a spacer block member mounted between said plate members, the exterior peripheral. outline of the base portions of the plate members and block member being identical and conjointly forming a dovetail fastening portion, bifurcated arm portions formed by said plate members, tool pockets formed between the bifurcated arm portions of the plate members and arcuate wall portions of said spacer block member, slot means formed in said bifurcated arm portions, pin means adjustably mounted in said slot means, the central longitudinal axes of said slot means being inclined to one another and intersecting one another in the work area between the bifurcated arm portions, said pin means being adjustable along said central axes of said slots, a gear train mounted in said tool holder and connecting said pin means, and the axes of rotation of said gear train being located along a substantially U-shaped arc.

2. The invention as defined in claim 1 and having positive synchronization means associated with said gear train permitting limited relative movement of the gear train relative to the tools supported by the Workholder in use.

3. A tool holder for roll forming tools or the like comprising: spaced arm portions defining a work cavity therebetween, pin means mounted on each of said arm portions, means adjustably supporting each of said pin means for movement toward and away from said work cavity, and wherein the means for one of said pin means comprises an elongated slot defined in part by substantially parallel side wall portions, said side wall portions being inclined to an imaginary line extending between the centers of said pin means and extending outwardly toward said work area away from said tool holder, and adjustment means fixedly securing said one pin means in any adjusted posit-ion within said slot.

4. The apparatus as defined in claim 3 and wherein having set screw means extending into engagement with said one pin means parallel to the side walls of said slot and having additional set screw means extending into engagement with said pin means at an angle inclined outwardly away from said tool holder relative to said side walls of said slot.

5. A tool holder for thread rolling tools comprising: spaced arm portions defining a work area therebetween, pin means mounted in each of said arm portions and adapted to rotatably support thread rolling tool-s in said work area, gear means for connecting said tools, intersecting gear cavities formed in said tool holder for each of the gear means, a closing plate secured on said tool holder and defining a pair of slots extending radially of said pin means, and a pair of guard members disposed in said slots and movable with said pin means and enclosing said gear means in said gear cavities in said tool holder.

6. Apparatus for roll forming threads on a workpiece comprising: tool holder means, spaced pin means supported by said tool holder means, thread forming rolls rotatably mounted on said pin means, gear means connecting each of said rolls, and positive synchronization 7 means connecting each of said rolls to said gear means so that said rolls will be positively synchronized during a thread forming operation regardless of the condition under which said rolls are initially brought into engagement with the workpiece, and wherein said synchronization means comprises sleeve means secured to said rolls and extending axially therefrom toward said gear means, opposed slot means formed in said sleeve means, lug

means abuttably engaged with said sleeve means in said slot means and connected to said gear means, spring means normally holding said lug means in abutting engagement with said sleeve means, and means permitting movement of said lug means away from abutting engagement with said sleeve means to compensate for variance in initial engagement conditions of said roll-s with said workpiece.

References Cited by the Examiner UNITED STATES PATENTS Re: 23,897 11/1954 Scott 80-6 2,694,322 11/1954 Nell 806 3,110,202 11/1963 Bedker 80-6 CHARLES W. LANHAM, Primary Examiner.

MICHAEL V. BRINDISI, Examiner. 

1. A TOOL HOLDER FOR THREAD ROLLING TOOLS OR THE LIKE COMPRISING STANDARDIZED SEPARABLE AND CHANGEABLE SPACED PLATE MEMBERS, A SPACER BLOCK MEMBER MOUNTED BETWEEN SAID PLATE MEMBERS, THE EXTERIOR PERIPHERAL OUTLINE OF THE BASE PORTIONS OF THE PLATE MEMBERS AND BLOCK MEMBER BEING IDENTICAL AND CONJOINTLY FORMING A DOVETAIL FASTENING PORTION, BIFURCATED ARM PORTIONS FORMED BY SAID PLATE MEMBERS, TOOL POCKETS FORMED BETWEEN THE BIFURCATED ARM PORTIONS OF THE PLATE MEMBERS AND ARCUATE WALL PORTIONS OF SAID SPACER BLOCK MEMBER, SLOT MEANS FORMED IN SAID FIBURCATED ARM PORTIONS, PIN MEANS ADJUSTABLY MOUNTED IN SAID SLOT MEANS, THE CENTRAL LONGITUDINAL AXES OF SAID SLOT MEANS BEING INCLINED TO ONE ANOTHER AND INTERSECTING ONE ANOTHER IN THE WORK AREA BETWEEN THE FIBURCATED ARM PORTIONS, SAID PIN MEANS BEING ADJUSTABLE ALONG SAID CENTRAL AXES OF SAID SLOTS, A GEAR TRAIN MOUNTED IN SAID TOOL HOLDER AND CONNECTING SAID PIN MEANS, AND THE AXES OF ROTATION OF SAID GEAR TRAIN BEING LOCATED ALONG A SUBSTANTIALLY U-SHAPED ARC. 